Google promised earlier this year it would give Nest users the option to migrate to more secure Google accounts, and the time has come to begin that process. The Nest app and website are both offering to migrate your account, but be warned, you cannot go back if you change your mind.
Migrating your account isn't necessarily hard, but there are numerous steps and a few caveats. You can access the migration wizard from the app or by signing into your Nest Home on the website. However, the web portal seems buggy at the moment. After moving to a Google account, you'll see the same home members and devices in the Nest and Google Home apps. Your Home devices will also link with your Nest hardware automatically in the future, without any additional steps. Nest subscriptions will also move to the Google Store.
If you were still clinging to any Works with Nest services, you'll have to kiss them goodbye to migrate. You'll also have to invite home members all over again, and they won't be able to use the Nest x Yale lock or Nest Secure keypad until they too finish the migration. So, make sure you don't lock anyone out. Because of the way Home accounts work, anyone you invite will be able to remove you from the account. That's not ideal.
While you can choose to remain on a Nest account, don't expect that to be viable forever. I would not be surprised if Google begins requiring migration for future Nest devices and features.